Mikaeus, the Unhallowed, Grimgrin, Corpse-Born, and Slumbering Walker

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Grimgrin, Corpse-Born on the battlefield
• Slumbering Walker on the battlefield

Steps

1. Activate Grimgrin by sacrificing Slumbering Walker
2. When Slumbering Walker dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect
3. Resolve the Grimgrin ability Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers